High purity molybdenum oxide, potassium molybdates, sodium molybdates and ammonium molybdates are of commercial inportance in synthesizing various molybdenum compounds of chemical grade for use in the production of molybdenum catalysts and for reduction to the metallic state, such as by hydrogen reduction, to produce a high purity molybdenum metal.
A variety of processes and purification techniques have heretofore been used or proposed for use for removing a variety of normally-occurring contaminating metals and/or contaminating metal compounds in technical grade molybdenum oxide concentrates. Such contaminating metals typically include potassium, manganese, lead, tin, calcium, magnesium, iron, copper and aluminum, the concentration of which varies depending on the particular ore body from which the molybdenite (MoS.sub.2) is obtained, and the type and severity of the beneficiation process by which the molybdenite ore is concentrated. Typical of such prior art processes for purifying technical grade molybdenum oxide concentrates are those described in U.S. Pat. Nos. 3,658,464; 3,829,550 and 3,848,049, which are assigned to the same assignee as the present invention. While the foregoing processes have been effective in reducing the concentration of contaminating metals and metallic compounds in technical grade molybdic oxide feed materials, there has been a continuing need for a purification process which is more efficient, which provides for increased yields of the purified molybdenum product, which is more economical to operate, and which reduces the volume of waste streams generated, thereby minimizing waste treatment operations with attendant further cost savings.
The present invention overcomes many of the shortcomings and disadvantages associated with prior art purification techniques by providing a process which is efficient, economical, simple to control, increases the yield of the purified molybdenum product produced, and wherein the purified product is substantially devoid of any residual contaminating metal or metal compounds therein.